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Yeast Cells Are Set to Fly for Space Experiment

It is perhaps fitting that a NASA satellite to carry yeast into orbit has roughly the shape and dimensions of a bread box.

The tiny 10-pound satellite known as PharmaSat will be hitching a ride aboard an Air Force Minotaur 1 rocket next to the main payload, a military reconnaissance satellite. Liftoff is scheduled for Thursday from a launching pad at Wallops Island in Virginia, after being postponed by weather Tuesday.

At first, the yeast cells will be comfortable space tourists inside PharmaSat’s microlaboratory, orbiting the Earth at a speed of 17,000 miles per hour and a height of 285 miles.

But then an antifungal drug will be injected into some of the yeast compartments, and instruments will measure how the yeast respond. Previous experiments on the space shuttle and the International Space Station indicate that some organisms become hardier and more virulent in outer space and more resistant to drugs.

Weightlessness might be changing how the drug reacts within the cells, or it might be switching on and off certain genes, resulting in greater resistance. Such effects will become of more concern to astronauts on longer-duration space flights like a mission to Mars.

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Yeast is used often for studying fundamental biological questions. On PharmaSat, the experiment will end after four days, and all of the yeast cells will die, probably within a week.

So-called nanosatellites like PharmaSat allow NASA to perform simple space experiments more quickly and cheaply than would be possible on the space station or a larger satellite. The entire cost of PharmaSat, including design, construction and operation of the satellite, is $3 million.

NASA first launched a nanosatellite, GeneSat-1, in 2006. Experiments on that satellite showed that keeping E. coli bacteria alive in a space microlaboratory was feasible. A future Ames-built nanosatellite, scheduled for launching next year, will look at how well biological building blocks and microbes survive when directly exposed to the radiation, vacuum and other rigors of space.

That will help test the idea that precursors of biological molecules rained down from the sky onto early Earth. By looking at how well microbes can survive in space, scientists can better evaluate a hypothesis that life may have first arisen on Mars and then was carried to Earth on a meteorite.